In a manufacturing process of a vehicle or the like, a welding gun attached to an arm tip of a robot is moved along a path programmed by teaching to weld workpieces. In the case of welding a new type of workpieces (to be referred to as a new workpiece), various operations such as teaching, determination of the position of a jig for supporting the new workpiece, design of the jig, and the like, are required. Because these operations increase worker-hours, reduction in worker-hours is desired.
One technique for shortening the worker-hours for preparatory operations before welding is disclosed in, for example, Japanese Laid-Open Patent Publication No. 2012-091304. Japanese Laid-Open Patent Publication No. 2012-091304 discloses, as a preparatory operation for welding a new workpiece, automation of a teaching operation and shortening of worker-hours by utilizing teaching information for existing workpieces (referred to as existing workpieces) with partial modification.